1. Field of the Invention
The present invention relates to a brushless motor having a resin bearing so that the torque output of a rotor suitable for driving a pickup of a portable mini disk apparatus can be transferred through a transfer device such as a gear.
2. Description of the Related Art
Referring to FIG. 5, in a conventional geared motor for driving a pickup of a portable mini disk apparatus, a pinion P is installed at a rotary output shaft S of a flat type brushless motor M as a transfer device to transfer the increased torque output. Also, although not shown, a pulley is installed instead of the pinion P for belt deceleration. In the motor having the above structure, a bearing holder H formed of brass is installed at a stator base B by caulking and the shaft S is installed for rotating through a sintered oilless bearing G.
In the above structure, however, due to the increasing cost of the brass bearing holder H and the sintered oilless bearing G, a resin bearing outsert-molded at the stator base is being adopted. However, as this resin bearing is not porous, maintaining oil is difficult and the oil adhering to the surface the bearing can easily leak.
To solve the above problems, it is an objective of the present invention to provide a brushless motor having a resin bearing in which the leakage of oil can be prevented with a simple structure without using a washer such as an oil stop so that the number of parts as well as the cost is reduced.
Accordingly, to achieve the above objective, there is provided a brushless motor having a resin bearing which comprises a rotor in which an output device is integrally formed at one side of a rotor case and a magnet is disposed at the other side thereof, a shaft for supporting the rotor, a resin bearing for supporting the shaft to be capable of rotating, a stator base incorporating the resin bearing, a stator for driving the rotor, and an oil containing portion formed at the resin bearing.
It is preferred in the present invention that at least a part of the oil containing portion is a plurality of grooves which are not consecutive and are formed at the inner surface of the resin bearing so that a lubricant is prevented from leaking in a direction in which a lateral pressure occurs during rotation.
Also, it is preferred in the present invention that at least a part of the oil containing portion is a concave portion disposed at a position corresponding to the bottom end of the shaft.
Also, it is preferred in the present invention that at least a part of the oil containing portion is an oil barrier device provided at an open end of the resin bearing.
Also, it is preferred in the present invention that the oil barrier device is a fluorine-based pigment coated around the shaft of the rotor case.